I have a problem that I cannot quite figure out............

Its is a 86 B2

Whenever the outside air temp reaches 95 the engine will shutdown after about 25 minutes of running. The internal engine temp is fine and it is not overheating though it shutdowns as though some safety feature has engaged. There is no gas going to the system during this time

If I let it sit for 60 mins or so and let it cool down it will restart just fine. Again it only happens when the outside air temp is 95+, at all other times it is just fine.
I have replaced the coolant tempature sensor and the air intake tempature sensor and flushed the system, it still persists. I replaced the coolant tempature sensor (the one to the computer)because I noticed that if I removed the wire to it the thing would restart after sitting for only 30 mins. If I put the wire back on the sensor too soon, it will not start, remove it again and it will restart, let it set for an hour or so with the wire on it and it will restart. BUT not stay started very long if the outside temp is still above 95. Leave the wire off after it cools down for a long period and it will not restart at all as it is just pooring gas into the system.

My next move is to replace the computer, any ideas and thoughts would be much appreciated before I invest in a new computer.

 

Good chance it's the TFI module. That's far more likely than the ECU, and cheaper too.

 

I would try the check engine lite codes if it has them, and When you say that it cuts out when it gets hot. Well It it has a electric fuel pump in the tank or frame rail or whatever, it might be going out. Or there could be a clog in the fuel system maybe the filter causing the pump to work harder and get hotter thus when the temp outside gets to a point it becomes too much and it quits till it cools down. I would. Um, try checking what the correct voltage the coolant sensor is supposed to send the computer then check what the voltage your senser is sending. Sounds like that is where your problems probably are. Check the wiring very closely and look for damage or bare spots. Could the wires be grounding out somewhere. Test the voltage at the sensor and at the other end of the wiring going into the computer. If it behaves differently like you say when you mess with the wiring, then thats probably close to the problem. Again check the sensor for proper operation, check the wiring, check all the voltage. If it has a check engine light that has the diagnostic feature you will have a slight advantage, just look in the repair manual and see what the codes say, they might help. Oh and just something to try, it sounds like its been leaving you stranded out and about. Find out what voltage the computer is supposed to recieve, and when it screws up on you, wire yourself some AA or AAA batteries in parallel or series, whatever will give you that voltage and plug that in to get you home. Its at least something to try if your so inclined, If all the above fails its probably the computer. If it does end up being that, when you pull it out and replace it, use the one that failed on you as a test to see if driving over it repeatedly will smash it. Good luck

 

I am sorry I forgot to mention, I replaced the YFI last year when this whole thing started.

Thank you though, should I move on to the computer?

 

In the beginning you said that the engine wouldn't start because it wasn't getting fuel. If that's still true, I would turn my attention to the fuel pump circuits and the fuel pumps (I'm pretty sure the '86 has two, low pressure pump in tank, high pressure on frame rail) and see why the engine isn't getting fuel. The fuel pump relay jumps to mind as a possible cause.